I need help feeding my 6 month old baby

She's been constipated all weeks, her poops come in pieces throughout the day and shes visible in pain when pooping. It's getting pretty bas and it makes me feel like I'm doing a bad job as a mom.

What I've been feeding her since starting solids: Mashed banana Yogurt Gerber purees (specifically apple, spinach and blueberries) I tried oatmeal but she hated it

My husband said that apparently banana it's really harsh on babies stomach's so today I only gave her yogurt

Edit: I didn't feed her banana thos morning and the consistency of the poop change.